A novel synthetic polymer (ethylene-vinyl acetate copolymer; EVA) was used to immobilize acclimated sewage sludge for H-2 production under anaerobic conditions. Using sucrose as the sole carbon substrate, the resulting EVA-immobilized cells achieved an optimal H-2 production rate (v(H2)) of 488 ml H-2/9 VSS and the best substrate-based yield (Y-H2/(sucrose)) of 1.74 mol H-2/mol sucrose. Operation at a temperature of 40 degrees C resulted in the most efficient H2 production. Acclimation of the sewage sludge allowed up to 3-fold enhancement on the performance of H-2 production. Kinetic studies show that a Monodtype model is able to describe the dependence of specific H-2 production rate on sucrose concentration. The immobilized cells maintained stable and efficient H-2 production during 15 repeated runs, indicating excellent durability and stability of the immobilized-cell system. The composition of soluble metabolites was found to be a reliable indicator for the efficiency of bichydrogenation. (c) 2004 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.